Ophthalmic Examination Instruments Copyright ©1999 by Larry Bickford. All Rights Reserved. This document may be copied one time for your personal use only. The publication must be copied in its entirety and include the copyright notice. Any use or sale for profit is strictly prohibited. PLEASE READ THIS: The information contained herein is not intended as a substitute for medical advice and care from qualified, licensed health care providers. The reader should regularly consult a physician in matters relating to his or her health and particularly with respect to any symptoms that may require diagnosis or medical attention. The information is presented here to educate and inform and to guide you to an understanding of cause, prevention as well as treatment. -------------------------------------------------------------------------- Instruments Commonly Used For Examination of the Eye by E. Lawrence Bickford, O.D. There are many instruments that the eye doctor might use to evaluate the eye and the vision system. This report presents some of the more commonly used items and includes some photographs of what this writer uses daily. It is divided in to two sections: instruments for the diagnosis of eye health and instruments used to determine the status of the vision system. Note: This report is under construction. Photographs are to help with identification. Models from various manufacturer's may appear somewhat different.

I will soon add additional photos providing examples of similar instruments from other manufacturers. Eye Health: Evaluation and Diagnosis Ophthalmoscope (aahp-thalmo-scope) There are two kinds of ophthalmoscopes: the smaller hand-help monocular direct (MO) and the larger binocular indirect (BIO). The MO is used to examine the back of the eye; that is, the optic nerve, blood vessels, the macula and the "fundus"---the general term for the back of the eye. The MO allows for a somewhat magnified view with limited viewing field. It can also detect changes in the clarity or obstructions in the normally transparent ocular media. The doctor must locate the instrument within a few millimeters of the pupil for viewing of the back of the eye and about 20-60cm in front for viewing the media. The BIO is an instrument which is either mounted on the doctors head or in a spectacle-type mounting like a virtual reality goggle. It has a separate light source and optical system and is used along with a condensing lens placed in front of the eye.

The doctor is positioned in front of the patient usually at a distance of 40-70cm (16-30 inches). Drops are most often used to dilate the pupil. This allows for a stereoscopic (3-D) view of the back of the eye. The image is somewhat reduced in size relative to the MO, but the field of view is far wider, allowing the examination of parts of the eye inaccessible with the MO. The stereoscopic ability also allows for the detection of elevated lesions that might not be apparent with the MO. The Slit Lamp Biomicroscope This instrument provides a high magnification view of the front structures of the eye, including the cornea, iris and lens, and with the use of the condensing lens, it allows a detailed, stereoscopic view of the retina. It is used to detect tissue damage to the ocular surface including the cornea (often with the use of yellow fluorecein, red rose bengal or green dye), conjunctiva and lids. It also can detect inflammation of the internal structures, cataract changes of the crystalline lens and more.

It is used extensively for the fitting of contact lenses and is the instrument of choice for detecting contact lens related tissue changes to the cornea and surrounding tissues. The Zeiss system (this one of the original Zeiss brand units) is shown on the left, a Haag Streit, a somewhat different design, is the picture on the right. A number of manufacturers make Zeiss-design and Haag Streit-design units. Visual Fields Tester Most eye doctors use some sort of automated visual field apparatus. Visual field testing is essential in determining retina disease or neurological deficits in the visual pathways between the eye and the brain. It is the primary tool for detecting visual field loss resulting from glaucoma, retinal tears, artery and vein occlusions and tumors along the optic nerve pathway and brain. Pictured here at the left is the Humphrey FDT unit (a recent addition to the ranks of computer-assisted field machines) It offers a very rapid screening protocol and fast full-threshold comparative testing (compared to the other devices). The patient observes an oscillating bar pattern which appears in various locations on a video screen in the unit and indicates that he/she sees the image by pressing a mouse button on a clicker.

Other field testers include the "big bowl" and "big box" units by a number of manufacturers. These are larger machines that display individual points of light on the inside of hemispherical shell. The patient sits with his/her head just inside the box and observes the light show and, as with the FDT, indicates seeing the target by pressing a mouse button. For all machines, a software program plots the observed targets in the field and uses a database to compare patient responses to expected age-relative normals. Tonometer This device measures the intraocular fluid pressure. The unit displayed here at the left is a portable version of the Goldmann type tonometer, the "gold standard" for diagnostic testing of eye pressure. Other Goldmann tonometers are mounted on the slit lamp. These units require the use of flourecein dye and, most often, a drop of topical anesthetic. There are a few other tonometers that are in use. Electronic probe contact-type machines are usually wall- or desk-mounted, provide a graphic print-out and do not require a local anesthetic. One newer version (shown on the right) is a pen-like probe (it looks like an electronic fever thermometer) that provides a digital read-out.

Some offices still use the "air puff" non-contact tonometer. This unit is valuable primarily as a screening tool. A note about pressure readings as they relate to glaucoma: Approximately 20% of diagnosed glaucoma patients have normal tension glaucoma (NTG). Their pressure appears within the normal range, but nevertheless suffer nerve damage and corresponding visual loss. There is also a pretty sizable population who have measured pressures above the "normal" range but do not have the visual or anatomical signs of glaucoma. Therefore, pressure readings alone are not a reliable method of diagnosing glaucoma. The disease is diagnosed by physical observation of the optic nerve and surrounding nerve fiber layer in the retina and by the analysis of the visual fields. Please see the article on The Glaucomas for more information. Instruments for the Determination of Refractive Error Keratometer and Automated Cornea Topographer The keratometer is shown here on the left. This instrument measures the curvature of the anterior cornea and is also useful in determining the smoothness of the ocular surface. Knowing the curvatures provides important information regarding the degree of astigmatism error.

The keratometer is useful in diagnosing keratconus, a cornea disease, and is vital in the fitting of contact lenses. The automated topographer (shown on the right) is a newer instrument which actually maps out the surface of the cornea, providing many additional data points relating the curvature changes at different locations. This information is displayed on a video screen and can be printed to hard copy. The instrument, not crucial for a standard examination or routine contact lens fitting, is becoming more widely accepted and is, arguably, a valuable tool. The automated topographer is very useful in verifying the diagnosis of keratconus and in preparation for laser refractive surgery. Retinascope This instrument is used to determine, objectively, the resultant additional lens power which presents the retina with a clearly focused image. In short, it determines the optical prescription with little or no viewer input. The unit projects a light source to the back of the eye as the operator dials in the lens power required to focus that light source correctly on the retina. Many doctors use this test routinely to give a starting point to begin the subjective refraction.

This is the comparative "which is better" test which allow the observer to modify the prescription lens power according to real-life and real-time needs. The automated refractor is a computer-controlled version of the retinascope and is often used, especially in a clinic or busy office settings. It is not necessarily more or less accurate than the hand-held unit. Unlike the manual unit where the examiner may observe fluctuations in the focusing system, the automated refractor simply averages a number of instantaneous readings. Software adjusts the data and prints out a "prescription". In a stable vision system, this data is highly reliable. In an unstable system, the data can be invalid; usually, the software so indicates. Either instrument is important in helping to determine the optical status of the eye. They are invaluable when examining non-communicative people, for example young children and disabled adults. The Refractor/Phoropter This instrument contains lenses and prisms which, in their various combinations, can reproduce virtually any possible optical correction. Here is where the data from the retinascope is placed and the viewer and the examiner subjectively adjusts the lens powers for optimum usefulness and patient comfort. The patient is asked questions comparing the quality of the vision afforded by two different lenses.

The examiner uses this information to fine-tune the lens powers to best suite the patient. The instrument also contains many other useful lenses. Some can be used to present a double image of the chart, allowing instant comparisons of the vision of the two eyes. Others help determine how the eye muscles respond to the various lenses placed in front of the eyes. These are the primary large instruments used to examine the eyes. The eye doctor also uses a number of other tools in his/her efforts to determine the health and refractive status of the eye and vision system. Ophthalmoscope - definition of ophthalmoscope by The Free Dictionary Ophthalmoscope - definition of ophthalmoscope by The Free Dictionary Related to ophthalmoscope: direct ophthalmoscope oph·thal·mo·scope (ŏf-thăl′mə-skōp′, ŏp-) n. An instrument for examining the interior structures of the eye, especially the retina, consisting essentially of a mirror that reflects light into the eye and a central hole through which the eye is examined. oph·thal′mo·scop′ic (-skŏp′ĭk), oph·thal′mo·scop′i·cal (-ĭ-kəl) adj.

oph′thal·mos′co·py (ŏf′thăl-mŏs′kə-pē, ŏp′-) n. ophthalmoscope Ophthalmoscope | definition of ophthalmoscope by Medical dictionary Ophthalmoscope | definition of ophthalmoscope by Medical dictionary Related to ophthalmoscope: direct ophthalmoscope ophthalmoscope [of-thal´mo-skōp] an instrument for examining the interior of the eye. direct ophthalmoscope one that produces an upright, or unreversed, image of approximately 15 times magnification. The direct ophthalmoscope is used to inspect the fundus of the eye, which is the back portion of the interior eyeball. Examination is best carried out in a darkened room. The examiner looks for changes in the color or pigment of the fundus, changes in the caliber and shape of retinal blood vessels, and any abnormalities in the macula lutea, the portion of the retina that receives and analyzes light only from the very center of the visual field. Macular degeneration and opacities of the lens can be seen through direct ophthalmoscopy. A, Inspection of the eye with a direct ophthalmoscope. B, Structures that are visualized.

From Polaski and Tatro, 1996. indirect ophthalmoscope one that produces an inverted, or reversed, direct image of two to five times magnification. An indirect ophthalmoscope provides a stronger light source, a specially designed objective lens, and opportunity for stereoscopic inspection of the interior of the eyeball. It is invaluable for diagnosis and treatment of retinal tears, holes, and detachments. The pupils must be fully dilated for satisfactory indirect ophthalmoscopy. scanning laser ophthalmoscope (SLO) an instrument for retinal imaging in which light from a low-power laser beam that scans the retina is reflected back to a sensor; the light detected by the sensor is used to create a full-color composite digital image. oph·thal·mo·scope [ophthalmo- + G. skopeō, to examine] ophthalmoscope /oph·thal·mo·scope/ (of-thal´mo-skōp) an instrument containing a perforated mirror and lenses used to examine the interior of the eye. direct ophthalmoscope one that produces an upright, or unreversed, image of approximately 15 times magnification.

indirect ophthalmoscope one that produces an inverted, or reversed, direct image of two to five times magnification. scanning laser ophthalmoscope an instrument for retinal imaging in which the retina is scanned by a low-power laser and the reflected light is used to create a digital image. ophthalmoscope (ŏf-thăl′mə-skōp′, ŏp-) n. An instrument for examining the interior structures of the eye, especially the retina, consisting essentially of a mirror that reflects light into the eye and a central hole through which the eye is examined. oph·thal′mo·scop′ic (-skŏp′ĭk), oph·thal′mo·scop′i·cal (-ĭ-kəl) adj. oph′thal·mos′co·py (ŏf′thăl-mŏs′kə-pē, ŏp′-) n. ophthalmoscope [ofthal′məskōp] Etymology: Gk, ophthalmos + skopein, to look a device for examining the interior of the eye. It includes a light, a mirror with a single aperture through which the examiner views, and a dial holding several lenses of varying strengths.

The lenses are selected to allow clear visualization of the structures of the eye at any depth. If the patient or the examiner ordinarily requires extensive correction of a refractive error, the examination may require that the corrective lenses should be worn for the examination. Also called funduscope . Ophthalmoscope [ophthalmo- + G. skopeō, to examine] ophthalmoscope An instrument capable simultaneously of illuminating and allowing observation of the inside of the eye. The direct ophthalmoscope is held as close as possible to the eye; the indirect ophthalmoscope is used at a short distance and requires the use of a separate hand-held image-forming lens. Ophthalmoscope An instrument used for viewing the inside of the eye that consists of a concave mirror with a hole in the middle through which the physician examines the eye, and a light source that is reflected into the eye by the mirror. Mentioned in: Eye Examination , Glaucoma , Papilledema , Physical Examination , Retinal Artery Occlusion , Retinitis Pigmentosa , X Rays of the Orbit ophthalmoscope An instrument for viewing the media and fundus of the eye.

It consists essentially of: (1) a light source (a halogen or tungsten bulb), a condenser system, a lens and a reflector (a prism, mirror, or metallic plate) to illuminate the interior of the eye, and (2) a viewing system comprising a sight hole and focusing system (usually a rack of lenses of different powers) to compensate for the combined errors of refraction of the patient and practitioner. See transillumination ; Visuscope . binocular indirect ophthalmoscope (BIO) An indirect ophthalmoscope with a binocular viewing system for obtaining a magnified, inverted, stereoscopic image of the fundus. It consists of a light source mounted above and between the examiner's eyes on a headset. This illuminates a handheld condensing lens of high positive power close to the patient's eyes, which forms an image of the patient's pupil in both of the examiner's pupils. An aerial image of the patient's fundus is formed between the condensing lens and the examiner (if the patient is emmetropic the image will be formed in the focal plane of the condensing lens). It appears inverted and stereoscopically through the oculars attached to the headset.

Stereopsis is obtained by reducing the interpupillary distance by means of mirrors or prisms within the headset of the instrument. This ophthalmoscope allows examination of a wide area of fundus and perception of depressed and raised areas (Fig. O1). confocal scanning laser ophthalmoscope (CSLO) An instrument using a confocal laser system to provide and analyse a three-dimensional image of the optic nerve head, peripapillary retina and macular region. The instrument uses a 670 nm diode laser and measures the amount of light reflected from a series of 16-64 optical sections in depth and reconstructs them to show the topography of the optic nerve head and a measure of the thickness of the retinal nerve fibre layer (RNFL). The RNFL thickness is compared with an age-matched normative database. The instrument is used to analyse RNFL defects, to detect damage to the optic nerve head and progressive changes over time in glaucomatous eyes, as well as retinal oedema, which occurs in the early stages of diabetic retinopathy. Syn. confocal scanning laser tomograph. See glaucoma detection; confocal microscope .

direct ophthalmoscope An ophthalmoscope that provides a virtual, erect image with a magnification of about ✕15 of the fundus, formed by the patient's eye in combination with whatever focusing lenses are needed to correct for the refractive errors of the observer and patient. The instrument is held at close range to the patient's eye and the field of view is small (less than 10º) (Fig. O2). The magnification M of a direct ophthalmoscope is equal to M = Fe /4where Fe is the power of the eye. Example: the magnification of the fundus of an aphakic eye of +40.00 D is equal to 40/4 = 10✕. indirect ophthalmoscope An ophthalmoscope that provides an aerial image of the fundus (and not the fundus itself as with a direct ophthalmoscope), which is real, inverted, with a magnification of ✕5 to ✕7 and formed at approximately arm's length from the practitioner. This aerial image is usually produced by a strong positive lens ranging in power from +13 D to +30 D that is held in front of the patient's eye.

The practitioner views this aerial image through a sight hole with a focusing lens to compensate for ametropia and accommodation. This instrument provides a large field of view (25-40º) and allows easier examination of the periphery of the retina. This instrument has been supplanted by the binocular indirect ophthalmoscope. The magnification of an indirect ophthalmoscope M is equal to M = Fe / Fcwhere Fe and Fc are the powers of the eye and of the condensing lens, respectively. Example: using a condensing lens of +15.00 D to view the fundus of an emmetropic eye yields a magnification of 60/15 = 4✕. See fundus camera ; inverted image . scanning laser ophthalmoscope (SLO) An ophthalmoscope that provides a continuous image of the ocular fundus on a TV monitor. It consists of a narrow laser beam, which is scanned horizontally and vertically to produce a rectangular area (called a raster) on the retina.

A small beam of light is reflected back out of the eye to a light detector, which monitors the brightness of each point on the raster and relays the information to the corresponding element on a TV monitor where the image can be viewed and/or stored. Low illumination is used to make this procedure more comfortable than conventional photography and mydriatics are usually unnecessary. The field of view extends up to 40 degrees. The instrument has been especially valuable in diagnosing glaucoma and in research. Fig. O1 Binocular indirect ophthalmoscope. The light source mounted above and between the examiner's eyes illuminates the condenser, which images the source at the periphery of the patient's pupil. The illumination does not overlap the observation beam. The condenser lens is handheld; it forms an inverted aerial image of the retina Fig. O2 Optical principle of the simplest form of direct ophthalmoscope (O, observer's eye; P, patient's eye; M, semi-silvered mirror) Table O1 Comparison between direct and indirect ophthalmoscopes ophthalmoscope [ophthalmo- + G.

skopeō, to examine] ophthalmoscope, (ofthal´məskōp´), n a device for examining the interior of the eye. It includes a light, a mirror with a single hole through which the examiner may look, and a dial holding several lenses of varying strengths. The lenses are selected to allow clear visualization of the structures of the eye at any depth. ophthalmoscope an instrument for examining the interior of the eye. It sends a bright, narrow beam of light through the lens of the eye, and contains a perforated mirror and lenses through which the veterinarian can examine interior parts of the eye. It is helpful in detecting possible disorders of the eyes, as well as disorders of other organs that are reflected in the condition of the eyes. direct ophthalmoscope one that produces an upright, or unreversed, image of approximately 15 times magnification. indirect ophthalmoscope one that produces an inverted, or reversed, direct image of two to five times magnification. What you can expect - Eye exam - Mayo Clinic What you can expect An eye exam usually involves these steps: You'll be asked about your medical history and any vision problems you might be experiencing.

Your eye doctor measures your visual acuity to see if you need glasses or contact lenses to improve your vision. You'll be given numbing drops in your eyes. Then your doctor measures your eye pressure. Your eye doctor checks the health of your eyes, possibly using several lights to evaluate the front of the eye and inside of each eye. To make it easier for your doctor to examine the inside of your eye, he or she will likely dilate your eyes with eyedrops. Your eye doctor discusses what he or she found during the exam and answers questions you have about your eyes. Part of the examination, such as taking your medical history and the initial eye test, may be performed by a clinical assistant. Several different tests may be performed during the eye exam. The tests are designed to check your vision and to examine the appearance and function of all parts of your eyes. Eye muscle test This test evaluates the muscles that control eye movement. Your eye doctor watches your eye movements as you follow a moving object, such as a pen or small light, with your eyes. He or she looks for muscle weakness, poor control or poor coordination.

Visual acuity test Visual acuity test Visual acuity test During a common test for visual acuity, your doctor has you read from a Snellen chart to determine how well you can see letters from across the room. This test measures how clearly you see. Your doctor asks you to identify different letters of the alphabet printed on a chart (Snellen chart) or a screen positioned some distance away. The lines of type get smaller as you move down the chart. Each eye is tested separately. Your near vision also may be tested, using a card with letters similar to the distant eye. The card is held at reading distance. Refraction assessment Refraction assessment Refraction assessment To determine your prescription for glasses, your doctor does a refraction assessment. He or she asks you to look through a mask-like device that contains wheels with different lenses of different strengths (phoropter) to help judge which combination gives you the sharpest vision. Light waves are bent as they pass through your cornea and lens.

If light rays don't focus perfectly on the back of your eye, you have a "refractive error." Having a refractive error may mean you need some form of correction, such as glasses, contact lenses or refractive surgery, to see as clearly as possible. Assessment of your refractive error helps your doctor determine a lens prescription that will give you the sharpest, most comfortable vision. The assessment may also determine that you don't need corrective lenses. Your doctor may use a computerized refractor to estimate your prescription for glasses or contact lenses. Or he or she may use a technique called retinoscopy. In this procedure, the doctor shines a light into your eye and measures the refractive error by evaluating the movement of the light reflected by your retina back through your pupil. Your eye doctor usually fine-tunes this refraction assessment by having you look through a mask-like device that contains wheels of different lenses (phoropter). He or she asks you to judge which combination of lenses gives you the sharpest vision. Visual field test (perimetry) Manual visual field testing Manual visual field testing During manual visual field testing, you look at a testing screen on which small flashes of light blink on and off at different locations.

You press a button each time you see a flash, and the test maps your responses and can identify gaps in your field of vision. Your visual field is the full extent of what you can see to the sides without moving your eyes. The visual field test determines whether you have difficulty seeing in any areas of your overall field of vision. The different types of visual field tests include: Confrontation exam. Your eye doctor sits directly in front of you and asks you to cover one eye. You look straight ahead and tell the doctor each time you see his or her hand move into view. Tangent screen exam. You sit a short distance from a screen and focus on a target at its center. You tell the doctor when you can see an object move into your peripheral vision and when it disappears. Automated perimetry. As you look at a screen with blinking lights on it, you press a button each time you see a blink. Using your responses to one or more of these tests, your eye doctor determines the fullness of your field of vision. If you aren't able to see in certain areas, noting the pattern of your visual field loss may help your eye doctor diagnose your eye condition.

Color vision testing You could have poor color vision and not even realize it. If you have difficulty distinguishing certain colors, your eye doctor may screen your vision for a color deficiency. To do this, your doctor shows you several multicolored dot-pattern tests. If you have no color deficiency, you'll be able to pick out numbers and shapes from within the dot patterns. If you do have a color deficiency, you'll find it difficult to see certain patterns within the dots. Your doctor may use other tests, as well. Slit-lamp examination Slit-lamp examination Slit-lamp examination Your eye doctor may use a microscope called a slit lamp to examine the front of your eye. The microscope focuses an intense narrow line of light on your eye. The slit lamp provides a magnified, 3-D view of the eye and allows your doctor to detect any small abnormalities. Used with an ophthalmoscope and special lenses, the slit lamp also provides detailed views of the back of the eye. A slit lamp is a microscope that magnifies and illuminates the front of your eye with an intense line of light. Your doctor uses this device to examine the eyelids, lashes, cornea, iris, lens and fluid chamber between your cornea and iris.

Your doctor may use a dye, most commonly fluorescein (flooh-RES-een), to color the film of tears over your eye. This helps reveal any damaged cells on the front of your eye. Your tears wash the dye from the surface of your eye fairly quickly. Retinal examination Indirect ophthalmoscopy Indirect ophthalmoscopy Your doctor holds your lids open and shines a bright light into your eye from a head-mounted instrument through a large lens. This allows your doctor to see a detailed 3-D view of the structures at the back of your eye. A retinal examination — sometimes called ophthalmoscopy or funduscopy — allows your doctor to evaluate the back of your eye, including the retina, the optic disk and the underlying layer of blood vessels that nourish the retina (choroid). Usually before your doctor can see these structures, your pupils must be dilated with eyedrops that keep the pupil from getting smaller when your doctor shines light into the eye. After administering eyedrops and giving them time to work, your eye doctor may use one or more of these techniques to view the back of your eye: Direct exam.

Your eye doctor uses an ophthalmoscope to shine a beam of light through your pupil to see the back of the eye. Sometimes eyedrops aren't necessary to dilate your eyes before this exam. Indirect exam. During this exam, you might lie down, recline in a chair or sit up. Your eye doctor examines the inside of the eye with the aid of a condensing lens and a bright light mounted on his or her forehead. This exam lets your doctor see the retina and other structures inside your eye in great detail and in three dimensions. Screening for glaucoma Applanation tonometry Applanation tonometry This test measures the amount of force needed to temporarily flatten part of your cornea. The test involves using a slit lamp equipped with forehead and chin supports and a tiny, flat-tipped cone that gently comes into contact with your cornea. This pressure measurement helps your doctor determine whether you may be at risk of developing glaucoma. Tonometry measures the fluid pressure inside your eye (intraocular pressure). This test helps your eye doctor detect glaucoma, a disease that damages the optic nerve. Several methods to measure intraocular pressure are available, including: Applanation tonometry.

This test measures the amount of force needed to temporarily flatten a part of your cornea. You'll be given eyedrops with fluorescein, the same dye used in a regular slit-lamp examination. You'll also receive eyedrops containing an anesthetic. Using the slit lamp, your doctor moves the tonometer to touch your cornea and determine the eye pressure. Because your eye is numbed, the test doesn't hurt. Noncontact tonometry. This method uses a puff of air to estimate the pressure in your eye. No instruments touch your eye, so you won't need an anesthetic. You'll feel a momentary pulse of air on your eye, which can be startling. If your eye pressure is higher than average or your optic nerve looks unusual, your doctor may use a pachometer. This instrument uses sound waves to measure the thickness of your cornea. The most common way of measuring corneal thickness is to put an anesthetic drop in your eye, then place a small probe in contact with the front surface of the eye. The measurement takes seconds. You may need more-specialized tests, depending on your age, medical history and risk of developing eye disease. Pediatric eye and vision examination. American Optometric Association.

Accessed Dec. 18, 2015. Clinical practice guidelines: Comprehensive eye and vision examination. American Optometric Association. Accessed Dec. 6, 2015. The difference between an ophthalmologist, optometrist and optician. American Association for Pediatric Ophthalmology and Strabismus. Accessed Dec. 18, 2015. Recommended eye examination frequency for pediatric patients and adults. American Optometric Association. Accessed Dec. 6, 2015. Jacobs DS. Open-angle glaucoma: Epidemiology, clinical presentation, and diagnosis. Accessed Dec. 18, 2015. Evaluation of the Ophthalmologic Patient. Merck Manual Professional Version. Accessed Dec. 18, 2015. Knoop KJ. Slit-lamp examination. Accessed Jan. 5, 2016. Elliott DB, et al. Evidence-based eye examinations. In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016. Elliott DB, et al. Assessment of visual function.

In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016. Elliott DB, et al. Ocular health assessment. In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016. Policy statement: Vision screening for infants and children. American Academy of Ophthalmology. Accessed Jan. 5, 2016. Policy statement: Frequency of ocular examinations. American Academy of Ophthalmology. Accessed Jan. 5, 2016. Robertson DM (expert opinion). Mayo Clinic, Rochester, Minn. Jan. 5, 2016. Related Overview - Eye exam - Mayo Clinic Visual acuity test Visual acuity test During a common test for visual acuity, your doctor has you read from a Snellen chart to determine how well you can see letters from across the room. Manual visual field testing Manual visual field testing During manual visual field testing, you look at a testing screen on which small flashes of light blink on and off at different locations.

You press a button each time you see a flash, and the test maps your responses and can identify gaps in your field of vision. Refraction assessment Refraction assessment To determine your prescription for glasses, your doctor does a refraction assessment. He or she asks you to look through a mask-like device that contains wheels with different lenses of different strengths (phoropter) to help judge which combination gives you the sharpest vision. Slit-lamp examination Slit-lamp examination Your eye doctor may use a microscope called a slit lamp to examine the front of your eye. The microscope focuses an intense narrow line of light on your eye. The slit lamp provides a magnified, 3-D view of the eye and allows your doctor to detect any small abnormalities. Used with an ophthalmoscope and special lenses, the slit lamp also provides detailed views of the back of the eye. Indirect ophthalmoscopy Indirect ophthalmoscopy Your doctor holds your lids open and shines a bright light into your eye from a head-mounted instrument through a large lens. This allows your doctor to see a detailed 3-D view of the structures at the back of your eye.

Applanation tonometry Applanation tonometry This test measures the amount of force needed to temporarily flatten part of your cornea. The test involves using a slit lamp equipped with forehead and chin supports and a tiny, flat-tipped cone that gently comes into contact with your cornea. This pressure measurement helps your doctor determine whether you may be at risk of developing glaucoma. An eye exam involves a series of tests to evaluate your vision and check for eye diseases. Your eye doctor may use a variety of instruments, shine bright lights directly at your eyes and request that you look through an array of lenses. Each test during an eye exam evaluates a different aspect of your vision or eye health. Pediatric eye and vision examination. American Optometric Association. Accessed Dec. 18, 2015. Clinical practice guidelines: Comprehensive eye and vision examination. American Optometric Association. Accessed Dec. 6, 2015. The difference between an ophthalmologist, optometrist and optician. American Association for Pediatric Ophthalmology and Strabismus. Accessed Dec. 18, 2015. Recommended eye examination frequency for pediatric patients and adults. American Optometric Association. Accessed Dec.

6, 2015. Jacobs DS. Open-angle glaucoma: Epidemiology, clinical presentation, and diagnosis. Accessed Dec. 18, 2015. Evaluation of the Ophthalmologic Patient. Merck Manual Professional Version. Accessed Dec. 18, 2015. Knoop KJ. Slit-lamp examination. Accessed Jan. 5, 2016. Elliott DB, et al. Evidence-based eye examinations. In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016. Elliott DB, et al. Assessment of visual function. In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016. Elliott DB, et al. Ocular health assessment. In: Clinical Procedures in Primary Eye Care. 4th ed. Philadelphia, Pa.: Elsevier Saunders; 2014. Accessed Jan. 5, 2016.

Policy statement: Vision screening for infants and children. American Academy of Ophthalmology. Accessed Jan. 5, 2016. Policy statement: Frequency of ocular examinations. American Academy of Ophthalmology. Accessed Jan. 5, 2016. Robertson DM (expert opinion). Mayo Clinic, Rochester, Minn. Jan. 5, 2016. Related Student Resource Glossary An analgesic that reduces pain and fever, but does not relieve inflammation. acupuncture A traditional Chinese medical practice using very thin acupuncture needles inserted into specific points of the body to restore the flow of qi. albuminuria The presence of the protein albumin in the urine. analgesic Refers to the class of drugs that relieves pain without affecting consciousness. antipyretic Medication administered to prevent or reduce fever. arthrocentesis A surgical puncture of the joint space to remove synovial fluid for analysis to determine the cause of pain or swelling in a joint. auscultation Listening for sounds within the body and is usually performed through a stethoscope. bacteriuria The presence of bacteria in the urine. bruit An abnormal sound or murmur heard during auscultation of an artery.

calciuria The presence of calcium in the urine. compliance The patient’s consistency and accuracy in following the regimen prescribed by a physician or other health care professional. computed tomography Use of a thin, fan-shaped x-ray beam that rotates around the patient to produce multiple cross-sectional views of the body. contraindication A factor in the patient’s condition that makes the use of a medication or specific treatment dangerous or ill advised. creatinuria An increased concentration of creatinine in the urine. echocardiography An ultrasonic diagnostic procedure used to evaluate the structures and motion of the heart. endoscope A small flexible tube with a light and a lens on the end. fluoroscopy The visualization of body parts in motion by projecting x-ray images on a luminous fluorescent screen. glycosuria The presence of glucose in the urine. hematocrit The percentage, by volume, of a blood sample occupied by red cells. hematuria The presence of blood in the urine. hyperthermia An abnormally low body temperature. idiosyncratic reaction An unexpected reaction to a drug that is peculiar to the individual. interventional radiology The use of radiographic imaging to guide a procedure such as a biopsy.

intradermal injection An injection made into the middle layers of the skin. intravenous injection An injection made directly into muscle tissue. ketonuria The presence of ketones in the urine. laparoscopy The visual examination of the interior of the abdomen with the use of a laparoscope that is passed through a small incision in the abdominal wall. lithotomy position The patient is lying on the back with the feet and legs raised and supported in stirrups. magnetic resonance imaging Uses a combination of radio waves and a strong magnetic field to create signals that are sent to a computer and converted into images of any plane through the body. ophthalmoscope An instrument used to examine the interior of the eye. otoscope An instrument used to visually examine the external ear canal and tympanic membrane. palliative A substance that eases the pain or severity of the symptoms of a disease, but does not cure it. parenteral Taken into the body, or administered, in a manner other than through the digestive tract. percussion A diagnostic procedure designed to determine the density of a body part by the sound produced by tapping the surface with the fingers. perfusion The flow of blood through an organ.

pericardiocentesis The puncture of the pericardial sac for the purpose of removing fluid. phlebotomy The puncture of a vein for the purpose of drawing blood. placebo An inactive substance, such as a sugar pill or liquid, that is administered only for its suggestive effects. positron emission tomography Combines tomography with radionuclide tracers to produce enhanced images of selected body organs or areas. prone position The patient is lying on the abdomen face down. proteinuria The presence of an abnormal amount of protein in the urine. pyuria The presence of pus in the urine. radiolucent The substance, such as air or nitrogen gas, does allow x-rays to pass through and appears black or dark gray on the resulting film. radiopaque The substance does not allow x-rays to pass through and appears white or light gray on the resulting film. rale An abnormal crackle-like lung sound heard through a stethoscope during inspiration. recumbent Any position in which the patient is lying down. rhonchi Coarse rattling sounds that are somewhat like snoring. Sims’ position The patient is lying on the left side with the right knee and thigh drawn up with the left arm placed along the back.

single photon emission computed tomography A type of nuclear imaging test that produces 3D computer-reconstructed images showing perfusion through tissues and organs. speculum An instrument used to enlarge the opening of any canal or cavity to facilitate inspection of its interior. sphygmomanometer Used with a stethoscope to measure blood pressure. stethoscope An instrument used to listen to sounds within the body. stridor An abnormal, high-pitched, musical breathing sound caused by a blockage in the throat or in the larynx. subcutaneous injection An injection made into the fatty layer just below the skin. transdermal Medication is administered from a patch that is applied to unbroken skin. transesophageal echocardiography An ultrasonic imaging technique used to evaluate heart structures. ultrasonography Imaging of deep body structures by recording the echoes of sound wave pulses that are above the range of human hearing. urinalysis The examination of the physical and chemical properties of urine to determine the presence of abnormal elements.

Question: Which instrument is used to examine the interior of the human eye?
Answer: AN OPHTHALMOSCOPE